Hearing Conservation – dBA Exposure Limits
Cal/OSHA requires hearing conservation measures when noise levels reach 85 dBA over 8 hours; 85 dBA is approximately the level of noise created by a lawn mower.
…from Safety Sanity’s ‘Hearing Conservation Safety Program’ (California):
“If exposures between 85 dBA and 90 dBA on an 8-hour time weighted average have been recorded, this requires the development of a hearing conservation program and the voluntary use of hearing protections devices.
If exposures in excess of 90 dBA on an 8-hour time weighted average have been recorded, mandatory use of hearing protection is required. Feasible engineering and administrative controls and a hearing conservation program shall be implemented. Impulse or impact noise levels over 140 dBA also dictate the preceding requirements as well.”
The following examples are estimates only, useful for general benchmarking and comparison purposes:
| dBA | |
| threshold of hearing | 0 |
| Whisper | 30 |
| Normal Conversation | 50-65 |
| Average Office | 55-60 |
| Lawn Mower at 10m | 60 |
| Laughter | 60-65 |
| Department Store | 65 |
| Hair Dryer at 1m | 70 |
| Chainsaw at 10m | 85 |
| Lawn Mower | 85-90 |
| Arc Welder, Food Blender | 90 |
| Hand Circular Saw at 1m | 95 |
| Farm Tractor | 98 |
| Jackhammer at 10m | 100 |
| Tablesaw | 105 |
| Chainsaw | 110 |
| Siren | 115 |
| Whistle at 1m | 120 |
| Oxygen Torch | 120 |
| Stadium Crowd (peak) | 130 |
| Aircraft Carrier Deck | 140 |
| Jet Takeoff at 25m | 150 |
| eardrum rupture | 150 |
| sound waves become shock waves | 194 |
Learn More:
Noise – Basic Information, from the Canadian Centre for Occupational Health and Safety: http://www.ccohs.ca/oshanswers/phys_agents/noise_basic.html
Cal/OSHA’s Exposure Limits for Noise: http://www.dir.ca.gov/Title8/5096.html
